package com.baizhi.homework;

/**
 * 电脑类
 */
public class Computer {
    private USB usb;

    public void setUsb(USB usb) {
        this.usb = usb;
    }


    public void on(){
        System.out.println("电脑开机了");
        if(usb != null){
            usb.service();
        }
    }


}
